Robotic garden tools, such as, but not limited to, robotic lawn mowers, are widely used to perform maintenance operations, such as lawn cutting, within predetermined working areas.
At present, boundary wires are often used to delimit the working area, and the robotic garden tool is arranged to move in a randomly generated irregular pattern to ensure complete coverage of the working area. There are also robotic garden tools moving in a partly systematic and partly irregular pattern.
However, when a working area comprises narrow passages interconnecting separated sub-areas of the working area, the robotic garden tool can get stuck in one sub-area for a substantial time. In the case of a robotic lawn mower this may lead to excessive cutting of the sub-area in which the lawn-mower gets stuck, and poor coverage of remote sub-areas.
There are several solutions available to minimize the above problem. One common solution is to let the robotic garden tool follow the boundary wire to a remote sub-area every time the mower leaves the charging station. This makes sure that the mower starts in the right place and it is a good way of increasing the ability to handle complex working areas.
WO 20111115563 A1 discloses a system in which a basic map of the working area is generated by means of a simple Global Navigation Satellite System, so as to enhance the boundary following. The system generates the starting position based on calculations of the size of working area and of how many times different points in the working area have been visited
A remaining challenge with the above mentioned solutions is that since the movement pattern of the robotic garden tool is random based and/or semi-systematic, the robotic garden tool may leave the remote sub-area almost immediately after arriving to it.
Accordingly, there remains a need for an alternative method and arrangement for enhancing a coverage distribution of a robotic garden tool.